Sodankylä AARDDVARK Receivers

The Sodankylä narrow-band VLF receivers are operated within the
framework of the Antarctic-Arctic Radiation belt (Dynamic) Deposition - VLF
Atmospheric Research Konsortia (AARDDVARK).
The nearest neighbours of our receivers are the Ny Ålesund
and the Cambridge UltraMSKs of British Antarctic Survey. Our long-lasting
collaboration with Lancaster University, U.K., has recently been extended: we
constructed one more receiver system, which is currently in test use at
Lancaster. It's final location is likely to be Scarborough.

SGO OmniPAL

Since 2002, there's a narrow-band VLF receiver operated by SGO. The
receiver was initially co-located with a VeloxNET synoptic VLF experiment
at Perunkajärvi near Rovaniemi, Finland, but later it was moved to
the main field station of SGO at Pittiövaara.

The receiver is an old "OmniPAL" (omnifarious phase and amplitude logger)
system hacked to run on Linux
(thanks to Janos Lichtenberger). It is capable of recording
amplitude and phase of up to six VLF transmitters at a maximum sampling
rate of 10 Hz. Since installed at Pittiövaara, the receiver has
been operated at maximum sampling rate all the time, because the unix-type
operating system allows for daily data retrieval and thus diskspace was not
an issue anymore. Currently we are monitoring the VLF transmitters with
callsigns NLK, NDK, NAA, NRK, GBP, and DHO (see figure for great-circle paths).

SGO UltraMSK Receivers

In 2007, SGO purchased two licences for the
UltraMSK receiver software. Receiver
aerials and the respective interface electronics were built
at SGO's workshop. The new aerials are
magnetic loops of 3 m × 3 m on wooden frames with 10 turns of coaxial
cable each. One of the receivers is placed at SGO. The other receiver was
first deployed at our measurement station of Pittiövaara for testing
before it was moved to Kilpisjärvi, which is
at the border to Norway, about 85 km from the EISCAT Ionospheric Heating
facility.

The new receives are able to monitor an arbitrary amount of transmitters,
limited by the processing capacity of the receiver computer. In our case we
are monitoring 11 stations simultaneously at the moment.
These are DHO, GBP, HWU, ICV, ITI, JXN, NAA, NDK, NLK, NPM, NRK.